An enhanced Sieve of Eratosthenes

This weekend, I showed my two oldest kids how to make a Sieve of Eratosthenes.  The oldest has been doing a lot of factoring, reducing fractions and decimal conversion, and it reminded me of when I learned about prime factorization.  I found reducing fractions to be a lot of guess work until I understood prime factors, and using the sieve not only helped me find prime numbers, but helped me understand factorization in general.

We actually modified ours a bit, since I wanted to focus on factorization, rather than just finding a bunch of primes. On our charts, instead of crossing out the composite numbers, we wrote down the prime factor that would have led to crossing out the number in the normal sieve.  This way, the kids now have a chart that shows, for all the numbers 1-100, either P for prime or the smallest factor otherwise.

6 thoughts on “An enhanced Sieve of Eratosthenes”

  1. I had never heard of a sieve of erathones. I quickly realized that I have been compiling lists like this on paper and in my head most of my life. I am going to make a modified sieve from 1-100 for my kids.

  2. Few things are more inspirational than browsing through your post here after a long day. Your fresh insight keeps me, and surely others, motivated and informed about Home Schooling. Don’t ever stop posting like this one on homeschooling charts, ok?

  3. I found your post on how to make a Sieve of Eratosthenes to be very informative. I knew the principles, but this makes it easy.


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